Author Sid | Last edit 10/02/2024 by Disisid
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Before we begin, we need to ensure you have an MQTT broker to communicate and test with. We can download MQTTX to ensure communication.
Ensure that the ESP32 dev library is installed, then go to libraries in the Arduino IDE and download PubSubClient.
Copy the full code into your IDE. Feel free to change things like the text it prints, etc
1 #include <WiFi.h>
2 #include <PubSubClient.h>
3
4 // WiFi
5 const char *ssid = "xxxxx"; // Enter your Wi-Fi name
6 const char *password = "xxxxx"; // Enter Wi-Fi password
7
8 // MQTT Broker
9 const char *mqtt_broker = "broker.emqx.io";
10 const char *topic = "emqx/esp32";
11 const char *mqtt_username = "emqx";
12 const char *mqtt_password = "public";
13 const int mqtt_port = 1883;
14
15 WiFiClient espClient;
16 PubSubClient client(espClient);
17
18 void setup() {
19 // Set software serial baud to 115200;
20 Serial.begin(115200);
21 // Connecting to a WiFi network
22 WiFi.begin(ssid, password);
23 while (WiFi.status() != WL_CONNECTED) {
24 delay(500);
25 Serial.println("Connecting to WiFi..");
26 }
27 Serial.println("Connected to the Wi-Fi network");
28 //connecting to a mqtt broker
29 client.setServer(mqtt_broker, mqtt_port);
30 client.setCallback(callback);
31 while (!client.connected()) {
32 String client_id = "esp32-client-";
33 client_id += String(WiFi.macAddress());
34 Serial.printf("The client %s connects to the public MQTT broker\n", client_id.c_str());
35 if (client.connect(client_id.c_str(), mqtt_username, mqtt_password)) {
36 Serial.println("Public EMQX MQTT broker connected");
37 } else {
38 Serial.print("failed with state ");
39 Serial.print(client.state());
40 delay(2000);
41 }
42 }
43 // Publish and subscribe
44 client.publish(topic, "Hi, I'm ESP32 ^^");
45 client.subscribe(topic);
46 }
47
48 void callback(char *topic, byte *payload, unsigned int length) {
49 Serial.print("Message arrived in topic: ");
50 Serial.println(topic);
51 Serial.print("Message:");
52 for (int i = 0; i < length; i++) {
53 Serial.print((char) payload[i]);
54 }
55 Serial.println();
56 Serial.println("-----------------------");
57 }
58
59 void loop() {
60 client.loop();
61 }
Hi, I'm MQTTX
to the ESP32.
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